--- a/gfx/wr/webrender/src/batch.rs
+++ b/gfx/wr/webrender/src/batch.rs
@@ -1114,36 +1114,40 @@ impl BatchBuilder {
                             let (uv_rect_address, _) = render_tasks.resolve_surface(
                                 ctx.surfaces[raster_config.surface_index.0]
                                     .render_tasks
                                     .expect("BUG: no surface")
                                     .root,
                                 gpu_cache,
                             );
 
+                            // Need a new z-id for each child preserve-3d context added
+                            // by this inner loop.
+                            let z_id = z_generator.next();
+
                             let prim_header_index = prim_headers.push(&prim_header, z_id, [
                                 uv_rect_address.as_int(),
                                 if raster_config.establishes_raster_root { 1 } else { 0 },
                                 0,
                                 clip_task_address.0 as i32,
                             ]);
 
                             let key = BatchKey::new(
                                 BatchKind::SplitComposite,
                                 BlendMode::PremultipliedAlpha,
                                 BatchTextures::no_texture(),
                             );
 
                             self.add_split_composite_instance_to_batches(
                                 key,
-                                &prim_info.clip_chain.pic_clip_rect,
+                                &child_prim_info.clip_chain.pic_clip_rect,
                                 z_id,
                                 prim_header_index,
                                 child.gpu_address,
-                                prim_info.visibility_mask,
+                                child_prim_info.visibility_mask,
                             );
                         }
                     }
                     // Ignore the 3D pictures that are not in the root of preserve-3D
                     // hierarchy, since we process them with the root.
                     Picture3DContext::In { root_data: None, .. } => return,
                     // Proceed for non-3D pictures.
                     Picture3DContext::Out => ()

new file mode 100644
--- /dev/null
+++ b/gfx/wr/wrench/reftests/split/order-3-ref.yaml
@@ -0,0 +1,15 @@
+---
+root:
+  items:
+    -
+      type: rect
+      bounds: [8, 8, 200, 200]
+      color: blue
+    -
+      type: rect
+      bounds: [8, 208, 200, 200]
+      color: blue
+    -
+      type: rect
+      bounds: [8, 408, 200, 200]
+      color: blue

new file mode 100644
--- /dev/null
+++ b/gfx/wr/wrench/reftests/split/order-3.yaml
@@ -0,0 +1,31 @@
+# Ensure that preserve-3d items are correctly batched with transparent siblings.
+---
+root:
+  items:
+    -
+      type: stacking-context
+      transform-style: "preserve-3d"
+      items:
+        -
+          type: rect
+          bounds: [8, 8, 200, 200]
+          color: blue
+    -
+      type: stacking-context
+      transform-style: "preserve-3d"
+      items:
+        -
+          type: rect
+          bounds: [8, 208, 200, 200]
+          color: blue
+    - type: rect
+      color: [255, 0, 0, 0.5]
+      bounds: [8, 408, 200, 200]
+    -
+      type: stacking-context
+      transform-style: "preserve-3d"
+      items:
+        -
+          type: rect
+          bounds: [8, 408, 200, 200]
+          color: blue

--- a/gfx/wr/wrench/reftests/split/reftest.list
+++ b/gfx/wr/wrench/reftests/split/reftest.list
@@ -14,8 +14,9 @@ skip_on(android,emulator) fuzzy(1,20) ==
 # Note: on windows the image is rendered at a slightly different spot.
 # similarly, a lot of tests in "transform" are non-windows. TODO: investigate
 platform(linux,mac) fuzzy(1,20) == same-plane.yaml same-plane.png
 #TODO: https://github.com/servo/webrender/issues/2946
 #== cross.yaml cross-ref.yaml
 == mixed-order.yaml mixed-order-ref.yaml
 fuzzy(1,40000) == filter.yaml filter-ref.yaml
 fuzzy(1,10000) == gradient.yaml gradient-ref.yaml
+== order-3.yaml order-3-ref.yaml